Jewish mysticism explains that sleep is the time when the body rests but the soul rejuvenates and strengthens.

Sleep is a pretty big deal. Today, experts agree that the average adult needs 7-9 hours of sleep per night for overall health. It’s not just about the quantity of sleep but the quality too. With a sound night’s sleep through all the cycles, we naturally boost our immune system, brain function and life satisfaction. But around one in three adults doesn’t get enough sleep. So what does that mean for someone’s sex life?

The Sainsbury’s Living Well Index conducted a study and found that people believe the two most determinant factors in a person’s happiness are sleep and sex.

The two are directly linked. According to the Sleep Foundation, not sleeping enough or well takes a hit on your sex life. Desire and arousal drop for women and men can experience erectile dysfunction. One study found that women’s sex drive increased by 14% with every extra hour of sleep. Other sleep studies have even linked lack of sleep to male infertility.

But sex can help.

Sex doesn’t just release bonding hormones, but calming ones too. Endorphins and oxytocin flood the system and induce relaxing, pleasant feelings- basically exactly what you need to fall asleep. Cortisol, the hormone associated with stress- the enemy of a good night’s rest, also subsides. Women especially can sleep longer and deeper, with the help of higher sex-induced estrogen levels.

Then there’s prolactin- the magical hormone that correlates to bigger orgasms, sexual satisfaction and making you sleepy post sex (shoutout to the men.) And it’s not just orgasm that does the trick either- it’s orgasm from partnered sex. Orgasm from intercourse had reported 400% higher levels of prolactin than orgasms from masturbation.

It’s not just the sex that helps you sleep, it’s the intimacy.

Hormonal releases can be enhanced when in a loving relationship- the closer you feel to someone, the easier you fall and stay asleep.

When people in a relationship sleep alongside each other, not only do they feel a greater sense of safety but their circadian rhythms (internal body clock) can sync up and promote harmony in the relationship. In fact, research found that among married couples, the happier the wife, the more aligned their sleep cycles were.

According to the lead author, Heather Gunn, “The sleep of married couples is more in sync on a minute-by-minute basis than the sleep of random individuals,” said Gunn. “This suggests that our sleep patterns are regulated not only by when we sleep, but also by with whom we sleep.”